I like shulk as well.
See I know mewtwo is strong in the right hands, but what i mean by better is that most of what people play are faster than him animation-wise, and my favorite combo(sideB+short hop+Fair) doesn't work often. I can play just fine and I win most games, just fast characters like pikachu, toon link, sheik, or zero suit I struggle with. Then there is always villager who I just hate with a passion. The teemo of Smash 4. I can beat him he's just FREAKING annoying.
Also I haven't practiced nearly as much with mewtwo as I should to be truly good with him. Lucario I lose ~3% of the time. The only people that I consistently have trouble with are palutena/pit, but I usually win. There isn't really a single character I lose to most of the time though